Inrush current has long been an issue for designers of electrical devices to deal with. When an electrical device is first turned on, that is, first provided power from a power source, the instantaneous current drawn by the device (known as the inrush current) is typically much larger than the steady state current drawn by the device. In some devices, inrush current is due to an input capacitance needing to charge. Once the input capacitance is charged, the current reaches a steady state.
Inrush current, if not compensated for or otherwise protected from, may cause damage to the electrical components of the electrical device. A variety of protection circuits and components are known in the art to limit, or in some cases eliminate, possible damage that may be caused by inrush current. Such circuits/components are vital to long-term operation and duration of electrical devices, particularly devices that turn on and off repeatedly over a period of time.